Landscaping with native and non-native plants

There is a growing trend of using "native" trees for landscape and conservation plantings. A native is a plant that naturally occurred in this area before European settlement. In contrast, other commercially available plants can either be cultivars (cultivated plants that are reproduced using cuttings or buds that are grafted onto separate root stock) or non-native (plants that were not part of the landscape prior to European settlement). Each of these plants has benefits and drawbacks.

Native species have evolved over thousands of years along with other indigenous plants and animals. They are adapted to the soils, rainfall, temperatures and environmental conditions in the areas where they have thrived. Utilizing native plants creates a natural, sustainable landscape that often offers beneficial food and cover for birds, butterflies and other wildlife.

The drawbacks of native plants are that some may be less resistant to the non-native insects and diseases that are now part of the landscape, such as dogwood borer, emerald ash borer or Dutch elm disease. Native plants may also be less able to tolerate the harsh growing conditions found in many urban areas, or they may not have the flowering or fruiting attributes that would make them highly desirable to some people.

Cultivated plants or cultivars have been developed to perpetuate desirable characteristics of a particular plant. Some of these desirable characteristics could be a striking flowering display, fruit production, disease resistance, form of tree or fall color. Cultivars offer predictability, so using them helps ensure that you obtain the desirable attributes you are looking for.

Most cultivars do not reproduce, but an exception is the Bradford pear, a cultivar that has become an invasive menace in forested communities.

Non-native trees have been brought to this country since the arrival of the first colonists. Some have become very important parts of the landscape, such as littleleaf linden or kousa dogwood, while others have become very undesirable invasive pests, such as the ailanthus (aka tree of heaven) or Norway maple.

Nonnative trees can be useful when the native variety is not well-adapted for the site. Examples of this might be using a Chinese chestnut to cultivate chestnuts instead of American chestnuts or employing the Chinese elm instead of the native American elm on a landscape where Dutch elm disease is a concern.

In some cases, the use of cultivars or non-native trees will simplify the maintenance requirements of a landscape since these plants can have resistance to insects or diseases or they have growth characteristics that would enable them to fit in their intended growth space without the need for corrective pruning.

Before planting any trees, analyze the site. How much growing space do you have? Is the site dry, wet or in between? Is it sunny or will the tree be growing in partial or full shade? What kind of soils do you have; are they sandy and well-drained or clay and poorly drained? Is the soil loamy and well-aerated, or is it hard and compacted due to heavy foot traffic?

Once you have determined the site conditions, you can decide if a native tree will suit your needs. If not, then the use of a cultivar or non-native tree might be a better alternative.

Nature Notes articles are written by members of the Frederick County Forestry Board.

Nature Notes for 7/15/2012